Continuous batch flash drier having coordinated feed and recycling means



1950 c. w. GORDON 2, 3 70 CONTINUOUS BATCH FLASH DRIER HAVINGCOQRDINATED FEED AND RECYCLING MEANS Filed Dec. 31, 1946 JNVENTOR.Charles W. Gordon Patented Dec. 26, 1950 CONTINUOUS BATCH FLASH DRIERHAVING COORUIINATED FEED AND RECYCLING MEANS Charles W. Gordon, GlenEllyn, Ill., asslgnor to Combustion Engineering-Superheater, 1110., acorporation of Delaware Application December 31, 1946, Serial No.219,346

v terial and 2 Eiaims. (Ci. 241-34) This invention relates to new anduseful improvements in drying apparatus and is particularly applicableto flash drying wet materials that are reluctant to give up theirmoisture.

In the usual flash drying apparatus hereto- However ing.

operation by turbulence.

moisture.

drawings, wherein:

proved flash drying system.

The system preferably omprises a disintegrator such as the cage mill Ainto which the material to be dried is conveyed in a current of hot gasand in which the material and gas are turbulently and intimatelycontacted; a separator B in which In the form fore employed, thematerial to be dried passes the ed. t a y d from e d tethrough theapparatus but once and is in congrator mill in the g t eam is Separatedm tact with the hot gaseous drying medium but for a the gas stream andfrom which the moisturevery small period of time, seldom more than sixladen gas is vented; a damper C for deflecting seconds. This shorttimefor the drying process lo the separated partly-dried material fromsepais adequate for most materials when subjected rator B back to thedisintegrator cage mill A or to an intimate and turbulent contact withthe deflecting the dried material out of the system; drying gases, suchas occurs when both the maa feeder D for delivering the raw wet materialses are passed through a cage mill. to be dried to the disintegratorcage mill A; and e are other materials which are l5 a furnace orotherheater E for heating the dryrelatively reluctant to give up theirmoisture, parlng gas. i ticularly the last few percentages of moisture,Reerring to Figure 1, the disintegrator A may, and these require morethan one stage of dryas here shown by wayof example, satisfactorily bein the form of a cage mill substantially of the One such system oftwo-stage drying is shown general type disclosed in thepatent to Gordonin my Patent 2,393,766, wherein two separate 2,149,018 granted February28, 1939. Suchacage cyclones are used one each for the two stages ofmill, shownin cross section, comprises a casing drying. The wet materialis partly dried in a I surrounding a chamber 2 within which is a firststage while passing through a first cyclone beater 3 mounted forrotation on the overhangwherein it is mixed with the separated dryinging end of a shaft 4 which is supported by beargases taken from a secondcyclone, and is thereings 5 outside of the casing I. The casing isproafter carried through a conveyor into the second vided with an inlet6 for the entry of the wet cyclone in suspension in a stream of hot drymaterial in suspension ina stream of hot gas and ases taken from anoutside source therein and a tangentially placed outlet 1 through whichthe dried in a second stage to a final moisture conpartly orsufficiently dried material leaves. tent. e mo -E e ases leave thesystem Shaft 4 is rotated by motor 8 and on the end through the vent ofthe first cyclone. If deof the shaft extending into the casing l issired, cage mills, as disclosed in the patent to mounted a hub 9 towhich is fastened a circular Gordon 2,149,018 or the like, may beintroduced plate in from which there extends across the into the ductsconveying the material to be dried 5, chamber of the casing a pluralityof rods ll. into the respective cyclones if a greater tur These rods arearranged in circles concentric bulence is required between the materialand hot with the shaft 4. At the periphery of plate in gases so as toeffect a greater drying. In genare mounted a multiplicity of fan bladesI! which eral, any multi-stage system of hash drying inlike the rods arearranged in a circ'e concentric W lv at least a muhiplicity f y l ninter 40 with the shaft 4 and extend across the chamber connected byconveyors and possibly theaddition 2 of casing I. In the particulardisclosure shown of cage mills, or the like, for improving the dryingthere are two sets of rods arranged in two concentric circles saidcircles b ing pc"d radia ly It is an object of thi i v n i n to providima art, a similar radial space being provided hel roved and simplifiedapparatus for flash dryin 1 tween the outermost rods II and the fanblades wet materials that are reluctant to give up their 12. l

Extending into the spaces between the sets of How the foregoing,together with other objects rods II and the fan blades it are other s tsof and advantagesas may hereinafter appear or are rods l3 connected tothe casing I. There ar= two incident to my invention are realized, isillussuch sets of rods arranged in concentric circles trated inpreferred form in the accompanying with respect to the former rods ll.

. of cage mill disclosed, only two sets of circularly- Figure 1 is adiagram showing the arrangement arranged rods ll rotate together withthe fan and interconnections of the apparatus of my imblades l2. Theremaining sets of circularly-arranged rods l3 remain stationaiy.

This general type of cage mill, as herein used in disintegrator A, isnot novel and in some forms both sets of rods M and it may be arrangedto rotate but in opposite directions. The fan blades !2 act to propelthe material and gases through the system. When drying some materials amultibladed fan may be used instead of the disin tegrator cage mill andprovide sufilclent turbulence to satisfactorily eirect drying.

In the illustrative system represented said disintegrator mill A issupplied with wet material in flotation in a stream of hot gas throughconduit it which connects to the disintegrator inlet 6. The wet materialis dropped into said conduit it through a conduit i5 into which saidmaterial is delivered by means of feeder D. Feeder D, which may be ofthe type shown in which belt or other conveyor it travels under a hopperl l which con tains the wet material to be dried, functions to withdrawthe material from said hopper at a predetermined rate. The feeder isdriven by a motor it.

Upon falling into the conduit Ed the wet mate= rial is conveyed byflotation in the stream of hotv gas coming from the heater E into thedisintegrai tor mill A. After being turbulently mixed with the hot aseswithin mill A the material is do livered from the disintegratcr milloutlet through conduit 59 into separator B. Device B may be cycloneseparator of the welldrnown type having a vent 29 at the top fordischarge of the moisture laden gases separated from the materialtherein and an outlet ill for removal of the partially dried orinsufiiciently dried material therefrom. [i duct 22 connected to theoutlet it of separator E de livers the partially dried material from theoutlet to the hot gas conduit is leading to the inlet cf disintegratormill A. Another duct 23 is con nected to the outlet M of separator B andremoves the sufficiently dried material from the system.

Means such as damper C comprising a divider vane 24 is provided at theoutlet of separator B and so arranged with respect to ducts 22 and 23that by the proper damper setting the partially dried material may beall deflected back into the hot gas conduit it via duct 22 or, if thematerial is sufficiently dried it may be all deflected into duct 23 andthence from the system. Such a damper may be a flap divider vane 2twhich, when in the position shown in the drawing, will deflect all ofthe partially dried material through duct 22 back to the mill A forrecirculation and further drying, and which when rotated to the rightwill deflect all of the sufficiently dried material from the systemthrough duct 23.

In operation, when starting the system up, the dividervane 24 is set toreturn all oi. the material passing out of the separator B back into thedisintegrator mill A via duct 22 and conduit M. The disintegrator mill Ais then placed into operation by starting motor 8. The feeder D is thenstarted and operated for a short time to feed raw wet material into thesystem via conduits i5 and 14. When a predetermined amount of materialhas been fed to the system the feeder D is stopped.

The material thus introduced into the system passes through thedisintegrator mill A, then through conduit i9 to separator 3 wherein itis separated from the gas and is thence returned via. duct 22 andconduit l4 into disintegrator mill A to pass through a second stage ofdrying and may thus be recycled through a number of subsequent stages,the number of stages of drying being predetermined for each material tobe stages the divider vane 24 is set to discharge the suificiently driedmaterial from the system through duct 23.

Simultaneously feeder D is started again to recharge the system and thecyclic operation is repeated as before until the subsequent batch issufficiently dried and removed from the system. These cycles arerepeated as often as is necessary to dry all of the material to bedried.

Preferably the operation of damper Cs divider vane 25 is made automaticand correlated with the operation'of the feeder D so that when thesufliciently dried material is being discharged from the system thefeeder will operate to refill the system and when the partially driedmaterial is being recirculated the feeder will be stationary so as notto admit additional material into the system.

One form of such automatic control may include a clock-operated switch26 which in timed intervals will make or break the electric current tosolenoids 21 and 28. Upon energizing the solenoids, the divider M isdrawn against a compression spring in into position (vertical as shown)to recirculate the material through the system and the switch contact 25is opened (against gravity) to stop the feeder motor l8. Upondeenergizing the solenoids, the divider vane 24 is returned by theaforesaid compression spring into position (its top rotated to theright) to discharge the dried material from the system and the switchcontact 29 is closed (by gravity) to start the feeder motor It so as torecharge the system with wet material.

The inlet temperature of the hot gas entering disintegrator mill A maybe controlled by temporing air dampers 38 which control the influx ofcold air through conduit 3! into the hot gas conduit it. The temperingdampers are located one each in the conduits H and 3| and areinterconnected by a rod 32 so that as one damper closes the other opens.The control of said dampers may be made responsive to thermostat 33located in the outlet conduit 20 of separator B. The

no variation in pressure due to the expansion of a gas in the thermostatis conveyed by tube 34 to a diaphragm motor 35 for moving the dampers.

Furthermore the said thermostat may control the amount of fuel to thefurnace E in order to 59 control the temperature of the hot gasesentering conduit M, either alone of supplementary to the aforesaiddamper control. In this case the tube {it will lead either directly fromthermostat 33 to the diaphragm motor 36 of the fuel control valve 31 orit will lead to both. the diaphragm motors 35 and 36.

By my improved system of drying wet materials that are reluctant to giveup their moisture, I accomplish the drying with a simple apparatus Wcomprising only a single disintegrator mill and a 55 tion has been shownand described, it will be dried. At the conclusion of the drying cyclesor 7 understood that changes in construction and organization of partsmay be made without departing from the spirit and scope of the inventionas claimed.

What I claim is:

1. In a. system for removing water from materials havins a high moisturecontent, the combination of a disintegrator mill, a fan and a separatorthrough which the material being dried flows in series; a. source of hotgases; a conduit for. conveying the hot gas from said source and saidmaterial in suspension therein into said mill; feeder means fordelivering the wet material to be dried into said hot gas conduit; aconduit through which said delivered material is carried in suspensionin said gas from said mill through the fan and to said separator; a venton said separator for removing therefrom the portion of said gas that istherein separated from said material; an outlet on said separator forremoving the separated material together with the remaining portion ofsaid gas that does not pass out of said vent; a first duct connectingsaid outlet directly with said hot gas conduit for returning partlydried material in flotation in the aforesaid remaining gas portion fromsaid separator to said mill for further drying a second duct connectedto said 0 outlet for removing sufficiently dried material from thesystem; a divider vane effective when in a first position to direct allof the partially dried material and said remaining gas portion from saidoutlet through said first duct into said hot gas conduit forrecirculation through and further drying in the system and effectivewhen in a second position to remove all of the sufliciently driedmaterial through said second duct from the system; means including acontrol device for placing said divider vane alternately in its firstand second positions for predetermined periods of time; and means alsogoverned by said control device for causing said feeder means to beinoperative while the divider vane occupies said first position toeffect the aforesaid recirculation of the partly dried material, andcausing said feeder means to operate while the divider vane occupiessaid second position to effect the aforesaid removal of the suflicientlydried material from the system.

2. In a system for removing water from materials having a high moisturecontent, the com bination of a disintegrator mill and fan and a cycloneseparator through which the material being dried flows in series, asource of hot gas, a conduit for conveying the hot gas from said sourceand said material in suspension therein into said mill, a feeder fordelivering the wet material to removing therefrom the portion of saidgas that is therein separated from said material, an outlet on saidcyclone for removing the separated material together with the remainingportion of said gas that does not pass out of said vent, a first conduitconnecting said outlet directly with said hot gas conduit for returningpartly dried material in flotation in the aforesaid remaining gasportion from the said cyclone to said mill for further drying, a secondduct connected to said outlet for removing sufliciently dried materialfrom the system, divider apparatus at said separator outlet effectiveunder a first control condition to direct all of the partially driedmaterial and said remaining gas portion from said outlet through saidfirst duct into said hot gas conduit for recirculation through andfurther drying in the system and effective under a second controlcondition to remove all of the sumciently dried material through saidsecond duct from the system, automatic means including a timing devicefor subjecting the aforesaid divider apparatus alternately to said firstand second control conditions during predetermined periods of time, andmeans also governed by said timing device for stopping said feederduring said first-control-condition time periods while the partly driedmaterial is recirculating and operating the feeder during said alternatesecond-control-condition time periods while the sufllciently driedmaterial is removed from the system.

7 CHARLES W. GORDON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain Dec. 2, 1931

